The present invention relates to a computer system having a storage system employing storage virtualization technology.
Amidst the rapid advancement of information systems through expansion of Internet business and electronic management of procedures, the data volume sent and received by computers is increasing exponentially. In addition to this kind of exponential increase in data volume, the data volume to be stored in storages is also increasing exponentially due to backup of data in disk devices (Disk-to-Disk Backup) and prolonged storage of business activity records (transaction information and emails) of companies required in audits. In connection with this, corporate information systems are seeking the reinforcement of storages in the respective business divisions/respective systems, and the simplification and streamlining in managing the complex IT infrastructure. In particular, expectations are increasing for technology capable of simplifying the management of storages and optimizing the total cost by utilizing the optimal storage according to the value of data.
As a method of reducing management costs of systems having large-scale storages, there is storage virtualization technology disclosed in Japanese Patent Laid-Open Publication No. 2005-011277. Japanese Patent Laid-Open Publication No. 2005-011277 discloses storage virtualization technology (hereinafter also referred to as “external storage connecting technology”) which connects a storage system (hereinafter referred to as a “first storage system”) connected to a host computer to one or more external storage systems (hereinafter referred to as “second storage systems”), virtualizing a device (hereinafter referred to as an “external device”) having a second storage system as though it is a logical device in the first storage system, and providing this to the host computer. When the first storage system receives an I/O request to the logical device from the host computer, it determines whether the device of the access destination corresponds to the external device in the second storage system, or corresponds to a physical device (internal device) such as a disk device mounted on the first storage system, and sorts the I/O request to the appropriate access destination according to the determination result.
As a result of using a storage system employing the external storage connecting technology described in Japanese Patent Laid-Open Publication No. 2005-011277, it is possible to create a system integrating a plurality of storage systems having different attributes such as performance, reliability, price and so on. For instance, it is possible to connect a high cost, high function and highly reliable first storage system using the external storage connecting technology and a low cost, low function and unreliable second storage system, logically hierarchize the storage extents, and optimally dispose data according to the update time of data and value of data. As a result of using the storage system having hierarchized storage extents, it is possible to store, for a long period of time, vast amounts of information such as transaction information and emails arising in the daily business activities with appropriate costs according to the value of each type of information for the purpose of dealing with audits.
Meanwhile, in order to store large capacity data across several ten years exceeding the life of the storage system, it will be necessary to replace the equipment configuring the computer system during the storage period of data. Japanese Patent Laid-Open Publication No. 2005-011277 discloses the copying and migration of data in a logical unit of the migration source storage (hereinafter referred to as a “migration source logical unit”) to a logical unit of the migration destination storage (hereinafter referred to as a “migration destination logical unit”) in order to replace the first storage system (hereinafter referred to as a “migration source storage”) employing the external storage connecting technology with another first storage system (hereinafter referred to as a “migration destination storage”).